Method of manufacturing an aged mattress assembly

ABSTRACT

Mattresses and methods for processing a flexible foam material for use in a mattress to provide a mattress foam material that has more consistent firmness over time and area. The methods include pre-conditioning the foam pad or mattress by applying a force across a substantial portion of a major surface of the mattress to compress or stretch the height of the foam, the length of the foam, and/or the width of the foam to break or open closed cells. In certain embodiments, the force is applied by repeatedly pressing a platen against the foam pad or placing the foam pad between one or more rollers.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 12/466,155, filed on May 14, 2009, which claimedthe benefit of the filing dates of U.S. Provisional Application No.61/192,575, filed on Sep. 19, 2008, and U.S. Provisional Application No.61/204,727, filed on Jan. 9, 2009. All of these applications are herebyincorporated herein by reference in their entirety.

FIELD OF THE INVENTION

This invention generally relates to cushioning articles such asmattresses and methods for processing a flexible foam material for usein a cushioning article so that it has more consistent firmness overtime and area.

BACKGROUND OF THE INVENTION

Today, furniture, and particularly bedding, manufacturers have developedsophisticated and reliable techniques for manufacturing high quality anddurable mattresses. The industry is capable of providing mattresses thatlast for over ten years providing comfortable sleeping surfaces for allthat time.

As the industry strives to continue providing improved quality andreliability, one area being addressed is the ability of the industry toprovide a consistent consumer experience across the lifetime of owningthe mattress, from the point of selecting the mattress until themattress is eventually replaced. When addressing the ability to providea consistent consumer experience for the entire lifespan of themattress, one engineering problem that needs to be addressed is thechanging characteristics of flexible foam over time. In particular, ithas been noticed by consumers that the mattress they select when testingmattresses on the showroom floor may have a firmness that differs, atleast somewhat, from the firmness of the mattress that ultimately isdelivered to their home after they purchase the mattress. Commonly, theconsumer finds that the mattress delivered to their home is more firmthan the mattress they tested on the showroom floor. Additionally, overtime the firmness of the mattress may change. As the consumer uses themattress, the mattress may develop areas where the mattress is less firmthan in other areas. Thus, over time the sleeping surface(s) of themattress can have an inconsistent feeling, one where the firmness of themattress varies or is perceived to vary.

Mattress manufacturers have circumvented this problem by educating theconsumer about the nature of foam and informing them that they shouldexpect the firmness of their newly purchased mattress to change overtime. However, this approach fails to address the underlying reasons forthe phenomenon and does not provide the consumer with a reliableestimate about how much the firmness of their new mattress is likely tochange.

Accordingly, there is a need in the art to provide for a mattress thatprovides a more consistent consumer experience yielding a firmness thatis consistent over time and over the full area of the mattress.

SUMMARY OF THE INVENTION

It is a realization of the invention that improved manufacturing andfinishing techniques can provide improved mattresses that have moreconsistent characteristics over time and area. Though not to be bound bytheory, this realization arises in part from the study of the cellstructure of foam. Foam is a cellular polymeric material. Polyurethanefoam is typically made by introducing tiny expandable gas bubbles into areacting mixture of a polyol, a polyisocyanate and other neededingredients. As the reactions proceed, a polymer matrix is formed andthe bubbles expand to give a cellular structure commonly called a foam.

The cellular structure is a network of interconnected cells made up ofstructural elements commonly called windows and struts. Theinterconnected cells in the foam structure have cell walls that havecommon openings or windows between them. Depending on manufacturingprocesses and the nature of the chemicals used, some of the cell windowswill be open while others may be closed by a thin film of thepolyurethane material. These closed cell windows can be broken orruptured by repeatedly stressing the material through compression and/orstretching such as those during the regular daily use of a mattress.Hence, a new or unaged mattress may have more closed cell windows than aused, aged mattress.

The cell structure thus formed can play an important role in determiningthe mechanical properties of the foam including its firmness orhardness. Hardness or firmness is typically measured by an indentationforce deflection test (IFD), which is a measurement of the load bearingproperties of the foam. In this test, a circular plate is depressed intothe foam to a desired depth or indentation. The test determines theforce required to reach a specified indentation. Alternatively, thecircular plate is depressed on a foam pad and applies a specified force.The indentation on the foam pad resulting from the force is measured.However, air may be trapped within the closed cells, and air flowthrough the foam may be limited if there is a large number of closed oronly partially open cells. Consequently, during IFD tests, additionalforce may be required to force the air out of the foam and the closedcells thereby generating an artificially high hardness or firmnessmeasurement that may change through normal use. If the same foam is thentested again, and again, the hardness is likely to go down a little biton each successive test cycle because the cell windows in the foam aregetting blown open or ruptured allowing air to pass through the foammore freely. Therefore, the IFD test measurements may effectivelyreflect the temporary pneumatic characteristics of these air-filledclosed cells rather than the eventual firmness of the used, aged foamwhen the cell windows have been broken through regular use.

Generally, foams used in automotive seating applications tend to bemolded foams designed to have a large population of closed cells whendemolded. If these cell windows are not crushed open immediately, thefoam pad is likely to lose dimensions and shrink. This is because carbondioxide gas gets trapped in the closed cells, cools down once the foamis demolded and then diffuses out from the cells faster than airdiffusing into the cells. Therefore, a pressure differential isgenerated between the outside and the inside of the cells causing thefoam to shrink. To reduce foam shrinkage, molded foam pads intended forautomobile seats are passed through rollers immediately after demoldingto drive out trapped hot gases such as carbon dioxide and therebyprevent foam shrinkage. However, foams used in mattresses or cushionsare not generally not made by such a molding process and consequentlyare not commonly thought to have carbon dioxide trapped in closed cells.Therefore, foam and mattress manufacturers have not thought to pass foammattresses or cushioning foam pads through rollers for pre-conditioningand stabilizing firmness.

As noted earlier, cell windows may be ruptured by repeatedly stressingthe material by compressing it and/or stretching it. Althoughcompression of a mattress or foam pad will rupture some of the cellwindows present in the foam, compression techniques adapted for use withmattresses or foam pads typically will only compress a mattress or padin one direction. For most mattresses and pads, this compressiongenerally will be in the direction of the smallest dimension, e.g. theheight of a typical mattress in a typical sleeping configuration. Inorder to increase the extent of cell window rupture, a mattress or foampad may be stressed along a plurality of physical axes, for examplealong as many of the three physical axes as possible. The aspect ratios(ratio of two physical dimensions, such as width to height, width tolength, or height to length) of typical mattresses and foam pads makeroller-based compression in the length and width directions difficultdue to buckling in the height direction. However, the very same aspectratio makes roller-based stretching in the length and width directionspossible. The system and methods described herein include compression orstretching techniques, or a combination of both techniques topre-condition or pre-stress mattresses or cushioning foam pads.

The systems and methods described herein include methods formanufacturing and finishing a mattress. The methods includepre-conditioning or accelerating the aging of the new, unaged foam pador mattress by applying a force across a substantial portion of a majorsurface of the mattress to temporarily compress the height of the foamand break or open closed cells. In certain embodiments, the force isapplied by repeatedly pressing a platen against the mattress or foampad. Alternatively, the force may be applied by passing the foam pad ormattress under at least one roller or through at least one complementarypair of rollers. The methods also include pre-conditioning the foam pador mattress by applying a force to stretch the length and/or width ofthe foam pad or mattress to break or open closed cells. The systems andmethods described herein overcome various limitations of current methodsby generating mattresses and cushioning articles having a firmness thatis substantially consistent over time and multiple uses and differentfrom the firmness of new, unaged mattresses and cushioning articles.

Accordingly, in one aspect, the invention provides methods of finishingand providing a mattress to a user that comprise providing an unagedmattress assembly having a first foam pad with an initial height and amattress core, accelerating the aging of the unaged mattress assembly byapplying a force to at least a section of the mattress assemblysufficient to temporarily compress its height an amount selected topermanently alter a mechanical property of the foam pad representativeof indentation force deflection, disposing the foam pad over themattress core to provide at least a portion of a sleeping surface overthe mattress core, and providing an aged mattress assembly having afirmness that is different from the firmness of the unaged mattressassembly. Optionally, the unaged mattress assembly further comprises asecond foam pad with an initial height, and stressing the unagedmattress assembly further comprises applying a force to at least asection of the second foam pad sufficient to compress the height of thesecond foam pad an amount selected to alter a mechanical property of thesecond foam pad, and disposing the second foam pad over the mattresscore. In certain embodiments, stressing the unaged mattress assemblycomprises applying a force to the mattress assembly sufficient tocompress the heights of one or more foam pads in the assembly an amountselected to alter one or more mechanical properties of the one or morefoam pads after the foam pads have been disposed over the mattress core.

In another aspect, the invention provides methods of manufacturing amattress that comprise providing a foam pad having an initial height,pre-conditioning the foam pad by applying a force to a least a sectionof the foam pad sufficient to temporarily compress the height of thefoam pad an amount selected to permanently alter a mechanical propertyof the foam pad, wherein the mechanical property may be representativeof the hardness or indentation force deflection. In certain embodiments,the foam pad may also be pre-conditioned by applying a force to at leasta section of the foam pad sufficient to stretch the length and/or widthof the foam pad by an amount selected to alter a mechanical property ofthe foam pad, wherein the mechanical property may be representative ofthe hardness or indentation force deflection. In another step, the foampad is disposed over the mattress core to provide at least a portion ofthe sleeping surface over that mattress core. In certain embodiments,the foam pad may be pre-conditioned by applying a force to at least asection of the foam pad sufficient to open the closed cells.

Optionally, the method may include pre-conditioning at least a secondfoam pad by applying a force to at least a section of the second foampad that is sufficient to compress the height of the foam pad and/orstretch the length and/or width of the foam pad by an amount selected toalter a mechanical property of that second foam pad. The second foam padmay also be disposed over the mattress core to provide a mattress havinga sleeping surface with multiple layers of pre-conditioned foamincluding two, three, four, or greater layers, with the number of layersselected to suit the application.

In another aspect, the systems and methods described herein will beunderstood to include a mattress having a pre-conditioned sleepingsurface. The mattress comprises a mattress core having a length, a widthand a thickness and at least one sleeping side, and a layer of foamhaving a length and a width substantially similar to the length and thewidth of the mattress core. The foam, once pre-conditioned in accordancewith an embodiment of the invention, also has a cell structure withcells having many ruptured windows being distributed substantiallyuniformly across its length, its width, and its thickness and the layerof foam is disposed over the sleeping side of the mattress core toprovide a sleeping surface of the mattress having a substantiallyconsistent firmness across the sleeping surface. Many cell windows maybe ruptured so as to increase the airflow through the foam pad and/or toreduce the pneumatic contribution to the foam pad's hardness orfirmness. Moreover, because many cell windows are already broken whenthe customer purchases the aged mattress assembly through the inventiveprocess described herein, further cell window rupturing due to thecustomer's use will be minimal and the customer will notice that thefirmness of the foam pad will not change significantly over time anduse, especially as compared with the firmness of an unaged mattressassembly with a majority of unbroken cell windows.

In one embodiment, the layer of foam comprises open cells resultant fromapplication of forces wherein each cell includes at least one cellwindow defining an interior cellular cavity and having at least oneopening sufficient to allow air to flow into and out of the interiorcellular cavity.

In another aspect, the invention provides methods of manufacturing amattress that comprise providing a foam pad having an initial length andwidth, pre-conditioning the foam pad by applying a force to a least asection of the foam pad sufficient to stretch at least one of the lengthand width of the foam pad an amount selected to alter a mechanicalproperty of the foam pad, wherein the mechanical property may berepresentative of the hardness or indentation force deflection. Inanother step, the foam pad is disposed over the mattress core to provideat least a portion of the sleeping surface over that mattress core. Incertain embodiments, the foam pad may be pre-conditioned by applying aforce to at least a section of the foam pad sufficient to open theclosed cells. Optionally, the foam pad may be pre-conditioned byapplying a first force to a first section of the foam pad sufficient tocompress the height of the first section a first amount selected toalter a mechanical property of the foam pad and by applying a secondforce to a second section of the foam pad sufficient to compress theheight of the second section a second amount selected to alter amechanical property of the foam pad.

Optionally, the method may include pre-conditioning at least a secondfoam pad by applying a force to at least a section of the second foampad that is sufficient to stretch at least one of the length and widthof the foam pad by an amount selected to alter a mechanical property ofthat second foam pad. The second foam pad may also be disposed over themattress core to provide a mattress having a sleeping surface withmultiple layers of pre-conditioned foam including two, three, four, orgreater layers, with the number of layers selected to suit theapplication.

In another aspect, the invention provides methods of manufacturing acushioning article that comprise providing a foam pad having an initiallength and width, pre-conditioning the foam pad by applying a force to aleast a section of the foam pad sufficient to stretch at least one ofthe length and width of the foam pad an amount selected to alter amechanical property of the foam pad, wherein the mechanical property maybe representative of the hardness or indentation force deflection. Incertain embodiments, the foam pad may be pre-conditioned by applying aforce to at least a section of the foam pad sufficient to open theclosed cells. Optionally, the method may include disposing at least onesecond foam pad over the first foam pad to provide a cushioning articlewith multiple layers of foam. In certain embodiments, the at least onesecond foam pad may be pre-conditioning by applying a force to at leasta section of the second foam pad that is sufficient to stretch at leastone of the length and width of the foam pad by an amount selected toalter a mechanical property of that second foam pad.

In all of the above aspects and embodiments, applying the force may beachieved by applying a deflecting, compressing, and/or stretchingmechanical force to the foam pad in one or more dimensions or applyingan increased gas pressure to the foam pad or by vacuum crushing the foampad. For example, in one embodiment, a roller or an indenting foot maybe used for applying a compressing mechanical force, and one or morerollers may be used to apply a stretching mechanical force. In anotherembodiment, the mattress or foam pad may pass through at least two pairsof counter rotating rollers, oriented parallel to each other andperpendicular to the passing direction of the mattress or foam pad. Inthis embodiment, the second pair of rollers has a higher tangentialvelocity than the first pair of rollers, which may resulting in theapplication of a stretching mechanical force. Optionally, the at leasttwo pairs of rollers may be oriented parallel to each other and parallelto the passing direction of the mattress or foam pad. In thisembodiment, the rollers rotate at the same tangential velocity but inopposite directions, acting to pull in opposite directions. The foam padbeing operated on may be any suitable foam pad, such as a flexible foampad, and may comprise a polyurethane foam, a visco-elastic foam, a latexfoam, a reticulated foam, water blown foam, polyethylene foam, a fiberpad, a gel or combination of any of these cushioning materials.

Applying the force can take place by pressing a platen against thesurface of the foam pad as well as by applying a roller that movesacross the surface of the foam pad or that uses at least one pair ofcounter-rotating rollers or with a belt or roller conveyor to providethe force. The force may be applied once or may be provided in a seriesof incremental steps that optionally may be periodic. In certainembodiments, each foam pad may be pressed and/or stretched separately ora group of foam pads may be pressed and/or stretched simultaneously. Thegroup of foam pads may be stacked on top of each other and thenpre-conditioned or pressed. In certain embodiments the foam pads may beprocessed or pre-conditioned in batches. In other embodiments, the foampads may be processed continuously as part of an assembly line.

In another aspect, the invention provides systems for pre-conditioningcushioning articles that comprise at least a first pair of rollers, afirst and second support frame, and a hinge system having at least onesupport spring. The at least one first pair of rollers includes a firstroller and a second roller, separated from each other by a first gap.The first roller is rotationally coupled to the first support frame andthe second roller is rotationally coupled to the second support frame.In certain embodiments, at least one of the first roller and secondroller is rotationally coupled to its respective support frame with atleast one freely rotating coupling. Optionally, at least one of thefirst roller and second roller is rotationally coupled to its respectivesupport frame via at least one roller driver coupling. In thisembodiment, at least one of the first roller and second roller may berotationally coupled to and actuatable by a motor assembly. In certainembodiments, the pre-conditioning system further comprises a pluralityof rollers including a second pair of rollers and a third pair ofrollers, wherein the first, second, and third pairs of rollers arearranged in a series configuration and have degrees of freedom in boththe vertical and machine direction regarding set points.

In certain embodiments, the first pair of rollers includes a first toproller and a first bottom roller, separated from each other by a gap ofabout 2 inches. The second pair of rollers includes a second top rollerand a second bottom roller, separated from each other by a gap of about1 inch, and the third pair of rollers includes a third top roller and athird bottom roller, separated from each other by a cap of about 0.5inch. The first, second, and third top rollers are coupled to a topsupport frame, and the first, second, and third bottom rollers arecoupled to a bottom support frame.

In certain embodiments, the first or top support frame and the second orbottom support frame is coupled to each other by an adjustable hingesystem. This adjustable hinge system includes at least one supportspring attached to the second or bottom support frame, and is configuredto exert a force on the second or top support frame sufficient tomaintain the first gap between the at least one first pair of rollers orthe spacing between the respective top and bottom rollers. Optionally,the first gap or spacing between gaps change in response to adjustmentsin the hinge system.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects and advantages of the invention will beappreciated more fully from the following further description thereof,with reference to the accompanying drawings wherein;

FIG. 1 is a photomicrograph of an open cell foam.

FIG. 2 graphically depicts the changes in load deflections of a materialbeing processed as being described herein.

FIG. 3 depicts one embodiment of a system for processing a foam pad.

FIG. 4 depicts an alternate embodiment of a system for processing a foampad.

FIG. 5 depicts a system for processing a mattress prior to packaging,according to an illustrative embodiment of the invention.

FIG. 6 depicts possible pressure points for a person lying down on amattress.

FIG. 7 depicts a posturized mattress, according to illustrativeembodiments of the invention.

FIG. 8 depicts one embodiment of a pre-conditioner apparatus forpre-stressing mattresses or foam cushioning articles.

FIGS. 9 a-9 d depict the apparatus of FIG. 8 from various perspectives.

FIGS. 10 a and 10 b depict an alternate embodiment of a system forpre-stressing mattresses or foam cushioning articles.

FIG. 11 is a flowchart of an exemplary pre-stressing process formattresses or foam cushioning articles.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The systems and methods described herein include, among other things,systems and methods for processing and finishing a foam material for usein a mattress to provide a mattress foam material that has moreconsistent hardness over time and area. Although the systems and methodsdescribed herein are described with reference to use with a mattress orsleeping surface, it will be understood by those of skill in the artthat the foam processing techniques and systems described herein may beapplied in other applications including other furniture relatedapplications for sofas, chairs, love seats, boat seats, and otherapplications.

Turning to FIG. 1, there is depicted a photomicrograph of an open-cellfoam material. Foam material may include polyurethane foam manufacturedfrom synthetic or natural raw materials or latex foam material.Polyurethane foam is typically made by introducing tiny expandable gasbubbles into a reacting mixture of a polyol, a polyisocyanate and otherneeded ingredients. As the reactions proceed, a polymer matrix is formedand the bubbles expand to give a cellular structure commonly called afoam.

The cellular structure, as shown in FIG. 1, is a network ofinterconnected cells of the foam material (e.g., polyurethane) made upof structural elements commonly called windows and struts. Theinterconnected cells in the foam structure have cell walls that havecommon openings or windows between them. Depending on manufacturingprocesses and the nature of the chemicals used, some of the cell windowswill be open while others may be closed by a thin film of thepolyurethane material. These closed cell windows can be broken orruptured by repeated compressions such as those during the regular dailyuse of a mattress. Furthermore, these closed cell windows may also bebroken by stretching of the foam structure.

As noted earlier, the cell structure thus formed can play an importantrole in determining the mechanical properties of the foam including itsfirmness or hardness. In particular, because of the temporary pneumaticcharacteristics of air-filled closed cells, foam may be harderinitially, but become softer after repeated use and after these cellwindows have been broken through regular use and aging.

Not to be bound by theory, but an understanding of the manufacturingprocess as set forth above illustrates that when first manufactured, thecells formed within the foam material have cell windows that arerelatively frail and subject to rupture upon application of stress. Itis understood that the rupture of these windows results in an increasein airflow through the polymer foam and therefore a change in thepneumatic characteristics of the cells within the foam. This can impactthe overall firmness of the foam. Thus, distributed throughout the foammaterial are cell windows that will rupture upon application ofsufficient stress to cause the windows to fail. As will be described ingreater detail hereinafter, the systems and methods described hereinprovide techniques for conditioning a foam pad and accelerating itsaging to rupture weak cell windows, thereby affecting the hardness ofthe foam pad such that later use will not result in a change, or asubstantial change, in the firmness of the pad. By preconditioning amattress pad across its length, width, and/or thickness it is understoodthat a consistent firmness for the pad may be provided across the fullarea of the foam pad. Generally, in the embodiments described herein,processes involved in conditioning, pre-conditioning, stressing,pre-stressing, and aging are similar, and may involve compression and/orstretching once or multiple times.

In one set of experimental data, the results of which are set forth inTable 1, a hexagonal roller test was applied to a foam pad that has notbeen prestressed to determine the effect of periodic and reciprocatingmechanical stress to the load deflection of the foam pad. In particular,in the data set forth in Table 1, a foam pad for a mattress wassubjected to a modified 100,000 cycles of a hexagonal roller procedureper ASTM F1566-99 Part 7 standard. The load deflection measurements wereobtained in accordance with ASTM F1566-99 Part 6 (center position) priorto testing, after 1,000 cycles and after 100,000 cycles. This wasaccomplished with a 13.5″ diameter circular platen. Height measurementswere gauged by applying a one pound contact force to the mattresssurface with the 13.5″ circular platen. The mattress was allowed torecover for one hour prior to height and deflection measurements.

TABLE 1 HEXAGONAL ROLLER TEST RESULTS: 100,000 CYCLE TEST % Change %Change % Change Deflection, Load (lbs) Load (lbs) (0-1000 Load (lbs)0-100,000 (1000-100,000 inches Initially 1000 cycles cycles) 100,000cycles cycles) cyc) 0.5″ 19.2 21.8 13.5 21.5 12.0 −1.4 1.0″ 44.6 35.2−21.1 30.9 −30.7 −12.2 1.5″ 57.7 48.2 −16.5 44.4 −23.1 −7.9 2.0″ 75.265.7 −12.6 61.3 −18.5 −6.7 2.5″ 93.3 83.6 −10.4 78.7 −15.6 −5.9 3.0″ 112102.4 −8.6 97.4 −13.0 −4.9 Average −11.2 −16.9 −6.4 Height @ 1 lb 10.9510.65 −0.30 10.51 −0.45 −0.14

As shown in Table 1, and as presented graphically in FIG. 2, thedeflection load of the foam pad changed substantially after the first1,000 cycles and reduced somewhat more after 100,000 cycles. As furthershown by the data set forth in Table 1, and graphically presented byFIG. 2, before application of the hexagonal roller, the load deflectiontesting indicates a break point at about 45 pounds of force. In certainembodiments, at this break point, a substantial number of cell windowsmay be ruptured and pneumatic contribution of the cells to the hardnessmeasurement is decreased. At that point, there is a change in the linearrate of deflection. Thus, the data indicates that prior to applicationof the hexagonal roller, the firmness of the mattress pad is non-linear,providing one level of support for loads below 45 pounds and a secondlevel of support for loads greater than 45 pounds. FIG. 2 shows thatafter testing for 1,000 cycles and the 100,000 cycles this non-linearityis removed and the support provided by the foam pad is linear from 20pounds throughabout 100 pounds of force.

This data is further reflected in Table 1. In particular Table 1 showsin one example that for 1.5″ of deflection an initial load of 57.7pounds was required. After cycling through 1,000 cycles, the necessaryload to achieve 1.5″ of deflection was reduced by 16.5% to 48.2 pounds.As further shown, an additional 7.9% reduction occurred after 100,000cycles wherein a force of 44 pounds was required to achieve 1.5″ ofdeflection. At this point, after 100,000 cycles, the foam materialrequired about 23% less force to achieve the 1.5″ deflection. To thisend, data measurements for other amounts of deflection are given inTable 1, as is the average, wherein it can be seen on average, after1000 cycles the amount of force to achieve deflection was reduced byapproximately 11.2% and after 100,000 cycles, was reduced by about 17%.As noted above, this result is understood to arise from a selectedrupture of cell windows that provides an improved sleep surface that ismore consistent.

In another set of experimental data, the results of which are set forthin Table 2, indentation load deflection (ILD) tests according toASTM3574-05: Standard Test Methods for Flexible Cellular Materials—Slab,Bonded and Molded Urethane Foams were performed on P165-30-type foam todetermine the effect of mechanical stress on the load deflectioncharacteristics of the foam.

TABLE 2 No. of passes 1 3 9 25% 25% ILD: 35.71 25% ILD: 32.63 65% ILD:63.08 65% ILD: 57.27 SF: 1.77 SF: 1.76 25%-65% 25% ILD: 35.32 25% ILD:27.01 65% ILD: 60.90 65% ILD: 49.84 SF: 1.72 SF: 1.85 25%-65%-85% 25%ILD: 34.12 25% ILD: 31.19 25% ILD: 26.49 65% ILD: 58.87 65% ILD: 55.4865% ILD: 46.59 SF: 1.73 SF: 1.85 SF: 1.76 65% 25% ILD: 31.88 25% ILD:30.46 25% ILD: 28.58 65% ILD: 54.94 65% ILD: 56.48 65% ILD: 52.65 SF:1.72 SF: 1.85 SF: 1.84 65%-85% 25% ILD: 28.83 25% ILD: 28.64 25% ILD:26.48 65% ILD: 52.12 65% ILD: 50.79 65% ILD: 46.69 SF: 1.81 SF: 1.77 SF:1.76 85% 25% ILD: 33.51 25% ILD: 31.35 25% ILD: 27.15 65% ILD: 59.27 65%ILD: 55.42 65% ILD: 50.30 SF: 1.77 SF: 1.77 SF: 1.85

In the data set forth in Table 2, a piece of P165-30 foam was subjectedto a compression prestress treatment comprising at least one 4-Hz passunder one or more rollers set to compress the foam to a certainpercentage ILD. The topmost row of Table 2 shows the number of passesthat the foam underwent, and the leftmost column indicates the type ofprestress treatment that was performed. For example, the “25%-65%-85%”row tabulates data from a piece of foam that was prestressed bycompressing to 25% ILD, then to 65% ILD, and finally to 85% ILD. The “3”column of that row contains data from a piece of foam that wasprestressed in this fashion three times; that is, three repetitions ofthe 25% ILD-65% ILD-85% ILD cycle. The initial characteristics ofP165-30 foam are 37.86 at 25% ILD, 65.01 at 65% ILD, and 1.72 supportfactor. As is evident from the data in Table 2, prestressing decreasesILD at both 25% and 65%, and as the number of prestressing cyclesincreases, the more ILDs decrease. Furthermore, multi-step prestresstreatments (e.g. 25%-65%, 25%-65%-85%, or 65%-85% treatments) decreaseILD more than single-step prestress treatments. As with the datatabulated in Table 1, these results are understood to arise from ruptureof cell windows due to prestressing.

FIG. 3 depicts one embodiment of a system 30 capable of processing afoam pad 32 to provide a more consistent and uniform firmness orhardness across the surface 34 of the foam pad 32 and for its usablelife as a mattress pad on a mattress. In particular, FIG. 3 shows amattress being made with a foam pad 32 fitted on top of a mattress core38. The mattress core 38 is seated on a table 40 above a moving platen42. In certain embodiments, the table 40 may be perforated so that airbeing pushed out of the foam pad 32 during compression can escapethrough the table 40. The platen 42 is capable of moving back and forthfrom the foot of the mattress to the head of the mattress and at thesame time, a mechanical arm 44 moves up and down as shown in FIG. 3. Themechanical arm 44 is capable of cyclically processing the foam pad 32 toapply a mechanical force. The amount of mechanical force applied isselected to adjust a mechanical characteristic such as the IFD of thefoam pad 32. As shown in FIG. 3, the platen 42 carried on the mechanicalarm 44 can move across the entire surface of the mattress, therebyprocessing the mattress across substantially its full length and width.This provides for a more consistent firmness across the full length andwidth of the mattress. In other embodiments, the foam pad may be firstprocessed individually, without the mattress core, and then disposed onthe mattress core to provide a conditioned mattress assembly.

In certain embodiments, the platen 42 is sized to be substantiallysimilar to the sleeping area of the mattress and/or the foam pad. Insuch embodiments, the system 30 may be used to pre-condition asubstantial portion of the mattress. Moreover, in such embodiments, thesystem 30 may be used to pre-condition the head, body and foot portionsof the mattress surface simultaneously. In other embodiments, the system30 may be configured as desired depending on the nature of thepre-conditioning. For example, the platen 42 may be sized and shaped toselectively pre-condition either a middle portion or edge portion orboth of a mattress and/or foam pad. In another example, the system 30may be configured with a plurality of platens 42 for pre-conditioningdifferent portions of the mattress by applying similar or differentloads. In certain embodiments, the platen 42 may be moveable along thelength or width of the mattress and equipped with a cylindrical rollersuch that the platen 42 may roll along the surface of the mattress toprogressively compress the mattress and/or the foam pad. Generally, inother embodiments and practices, it could be that the device shown inFIG. 3 merely processes selected portions and areas of the foam pad 32.In certain embodiments, the mattress may be posturized such that themattress may be configured with a plurality of zones of varyingfirmness. In such embodiments, the mattress may be posturized withselected zones having different firmnesses from other zones to promotenatural alignment of the S-curve of your spine by adding extra supportin the lower back and under the knees or to provide varying firmnesszones for partners that sleep on the same mattress but desire differentfirmness. It will be apparent to those with skill in the art that theareas processed on the foam pad 32 will depend on the application andcan vary as desired. In certain embodiments, more foam pads (not shown)may be further disposed on the mattress to provide multiple layers offoam. Optionally, one or more of these additional foam pads may also bepre-conditioned by stressing, compression, and/or stretching asdescribed in this application, to provide a mattress with multiplelayers of pre-conditioned foam.

FIG. 4 depicts an alternate system for processing a foam pad. In thedepicted embodiment a pair of counter-rotating rollers apply a forceacross the full length and width of the foam pad. The rollers canoptionally be placed into the foam manufacturing, cutting or shippingassembly line so that newly manufactured foam is processed as it isbeing prepared in the factory. In still a further embodiment andpractice, the foam pad may be subjected to a vacuum crushing processthat uses the force of a vacuum to alter the selected mechanicalproperty. As known to those of skill in the art, vacuum processing maybe achieved by placing newly manufactured foam into a chamber. Thechamber can support a vacuum and the foam inside the chamber issubjected to the force of the vacuum, causing the foam to be crushed ina process that causes the rapid expansion of the foam within thechamber. In the presence of the vacuum, the gas inside the foam cellsmay cause the foam to expand and when the vacuum is dropped, the foammay return to its original shape and rupture intact cell windows alongthe way. In other embodiments, the foam pad may processed using gaspressure instead of vacuum. In this embodiment, the foam pad may beplaced into a chamber that can support high gas pressure. The chamber ispressurized to a high gas pressure, which causes the foam to be crushedand foam cell walls to be ruptured. Still other techniques andcombination of techniques may be used with the systems and methodsdescribed herein without departing from the scope of the invention.

FIG. 5 depicts a system 50 for processing a mattress prior to packaging,according to an illustrative embodiment of the invention. In particular,system 50 includes a mattress 62 placed on a conveyor 51. The mattressmay be a finished mattress 50 product having a mattress core and/or oneor more layers including one or more of a ticking layer, foam pad,backing layer and fire retardant layer. The system 50 further includes acompression assembly 53. The assembly 53 includes a platen surface 66and one or more rollers 58 mounted on legs 64. The system 50 alsoincludes a packaging apparatus 72 for packaging or bagging thepre-conditioned mattress product. The system 50 may further include oneor more sensors, such as a height sensor, disposed at various location'salong the conveyor 51. During operation, the mattress 62 moves along theconveyor 51 and towards the compression assembly 53. The mattress 62 mayundergo one or more discrete or continuous compressions at thecompression assembly 53. In one embodiment, the platen 66 bends alonghinge 60 to first compress the mattress 62. The platen 66 may also bedisposed at an angle with the conveyor 51 such that the distance betweenthe conveyor 51 and the platen 66 decreases along the length of theconveyor 51. Systems 30 and 52 described with reference to FIGS. 3 and4, respectively may also be used in combination with system 50.Following compression, the mattress 62 may be allowed to decompress andrecover. Upon recovery, the mattress 62 may be packaged at the packagingapparatus 72.

FIG. 6 depicts a diagram of a person lying down on a mattress. When aperson lies on a flat, noncompliant surface, his or her entire weight isgenerally primarily supported by several points of contact with thesurface. For example, a person lying on his or her back on a flatsurface may be primarily supported by his or her head, shoulders,buttocks, and calves. These portions of the body may experience higherpressures due to this contact, and after prolonged contact, this mayresult in discomfort. If the surface is a mattress or a cushioningarticle, these pressures are moderated somewhat due to the compliantnature of the mattress or cushioning article. However, even in thiscase, textural or firmness adjustments made to the mattress orcushioning article at these points of contact may help alleviatediscomfort. Such a mattress is known as a posturized mattress.

FIG. 7 depicts a top-down view (top) and a side view (bottom) of aposturized mattress 700 according to an embodiment of the invention.Posturized mattress 700 includes a mattress core 706 and a posturizedfoam pad 702 disposed upon the mattress core 706 to provide a sleepingsurface. Portions 704 and 706 of the foam pad 702 may be processeddifferently. For example, portion 706 of the foam pad 702 may bepre-stressed, whereas portion 704 is not pre-stressed. This results in aposturized mattress where certain portions of the mattress are firmer orsofter, and may be tailored to match a user's sleeping posture. In otherembodiments, different portions of the foam pad or mattress may bepre-stressed to different extents. For example, one section of themattress and/or foam pad may be compressed (or stretched) a certainamount to provide a particular firmness, and another section of the samemattress and/or foam pad may be compressed or stretched by a differentamount to provide a different firmness. Optionally, a mattress and/orfoam pad may be pre-stressed in more than two portions, and each portionmay be pre-stressed to provide a different firmness. In certainembodiments, the mattress core 706 may also be posturized.

FIG. 8 depicts an exemplary pre-conditioner apparatus 800 forpre-stressing mattresses and foam cushioning articles. Exemplarypre-conditioner apparatus 800 includes three pairs of counter-rotatingrollers 802, 804, and 806, but it should be understood that the numberof rollers or pairs of counter-rotating rollers may be varied withoutdeparting from the scope of the invention. The roller pairs 802, 804,and 806 may be disposed such that the roller pairs are substantiallyparallel to each other, and oriented so that a mattress, foam pad, orother item that passes through one roller pair during the normal courseof operation will also pass through the other roller pairs. One rollerfrom each pair of rollers 802, 804, and 806 may be rotationally coupledto a first support frame 808. The other roller from each pair of rollers802, 804, and 806 may be rotationally coupled to a second support frame814. In certain embodiments, the rollers from roller pairs 802, 804, and806 coupled to the first support frame 808 may instead be rotationallycoupled to one or more roller drivers or mounts, which may be in turncoupled to first support frame 808. Likewise, the rollers from rollerpairs 802, 804, and 806 coupled to the second support frame 814 mayinstead be rotationally coupled to one or more roller drivers or mounts,which may be in turn coupled to second support frame 814. One or morerollers in each roller pair may be allowed to rotate freely.Alternatively, one or more rollers in each roller pair may be actuatedby a motor or some other actuation device. In certain embodiments, theone or more rollers coupled to either the first or second support framesmay have degrees of freedom in the vertical and/or horizontal or machinedirection. In these embodiments, the one or more rollers may beadjustable in a vertical direction, so that roller pair gap spacing canbe changed or the entire roller pair can be shifted vertically up ordown with respect to the support frames and/or the entire apparatus.Optionally, the one or more rollers may be adjustable in a horizontal ormachine direction, such that the horizontal spacing between roller pairscan be adjusted. In certain embodiments, the horizontal positioning ofthe individual rollers within a roller pair may be adjustedindependently, such that one of the rollers may be shifted horizontallywithout a corresponding shift in the other roller, or both rollers maybe shifted in opposite directions.

In certain embodiments, first and second support frames 808 and 814 maybe physically linked to each other by hinges 810 and spacers 812.Support springs 811 may apply a force to a portion of first supportframe 808 to maintain a particular separation between thecounter-rotating rollers in each of roller pairs 802, 804, and 806.Spacers 812 may hold one or more positioning markers 813, which may aidin maintaining the separation between the counter-rotating rollers ineach roller pair. In certain embodiments, positioning markers 813constrain the vertical movement of first support frame 808. Optionally,positioning markers 813 may assist in supporting first support frame 808so as to maintain a particular roller separation.

Spacers 812 may be configured to hold positioning markers 813 in aplurality of positions, with each position corresponding to a desiredroller-roller spacing within a particular roller pair. The force exertedon first support frame 808 by springs 811 may enable efficient and quickreadjustment of roller-roller spacing within the roller pairs 802, 804,and 806. The roller-roller spacing within each roller pair may beadjustable by a number of methods. For example, the roller-rollerspacing of all the roller pairs may be adjusted simultaneously bychanging the position of positioning markers 813 on spacers 812.Optionally, the roller-roller spacing of individual roller pairs may beadjusted by moving the individual rollers rotationally coupled to firstsupport frame 808 vertically up or down. Roller-roller spacing may beset in order to compress a mattress or foam pad by a certain amount orto exert a certain force on the mattress or foam pad. In certainembodiments, the rollers in roller pair 802 may be separated by a gap ofabout 2 inches, the rollers in roller pair 804 may be separated by a gapof about 1 inch, and the rollers in roller pair 806 may be separated bya gap of about 0.5 inches.

Platform 816 may be attached to second support frame 814. In thisexemplary embodiment, platform 816 is a stationary platform on which amattress or foam pad being processed may rest. In certain embodiments,platform 816 may be replaced by a multi-roller system or a conveyor beltto more easily transport mattresses or foam pads being processed.

The rollers in roller pairs 802, 804, and 806 may rotate such that theirtangential velocities are substantially similar. In certain embodiments,the rollers in a particular roller pair may rotate such that theirtangential velocities differ from those of the rollers in another rollerpair. For example, the rollers in roller pair 804 may operate with lowertangential velocities than the rollers in roller pair 806. Thus, amattress or foam pad being processed may not only be compressed byroller pairs 802, 804, and 806, it may also be stretched in alongitudinal direction due to the differing tangential velocities ofroller pairs 804 and 806. Similarly, roller pairs may operate withdiffering tangential velocities in order to compress a mattress or foampad in a longitudinal direction. In certain embodiments, the differingtangential velocities may be selected to stretch a mattress or foam padwith an initial length and width by an additional length and/or widthchosen to provide a particular final mattress/foam pad firmness.

FIGS. 9 a-d depict the exemplary apparatus of FIG. 8 from a number ofdifferent perspective views.

FIGS. 10 a-b depict an optional implementation 1000 of a mattresspre-stressing apparatus according to the invention. FIG. 10 a is a viewof optional implementation 1000 from above, and FIG. 10 b is a view ofoptional implementation 1000 from one side. Implementation 1000comprises at least two counter-rotating roller pairs 1002 and 1004.Roller pairs 1002 and 1004 may include spiral features 1006 and 1008which extend from each of the rollers of roller pairs 1002 and 1004.When a mattress or foam pad 1010 is being processed, roller pairs 1002and 1004 rotate so as to pull mattress or foam pad 1010 to theirrespective sides. For example, roller pair 1002 may rotate so as to pullmattress 1010 toward the left side, and roller pair 1004 may rotate soas to pull mattress 1010 toward the right side. The spiral features 1006and 1008 may act to pull the mattress along a direction parallel to theroller pairs, as indicated by the straight, double-ended arrow in FIG.10 a. Thus, a mattress or foam pad 1010 may be transported in alongitudinal direction (straight double-ended arrow) while beingstretched in a substantially transverse direction (perpendicular tostraight double-ended arrow).

FIG. 11 is a flowchart of an exemplary pre-stressing process 1100according to the invention. After the start of the process (step 1102),a mattress or foam pad being processed in the exemplary apparatus ofFIG. 8 may be compressed vertically by roller pairs 802,804, and 806(step 1104). Optionally, the mattress or foam pad may also besimultaneously stretched in a direction perpendicular to the rollerpairs by roller pairs 802, 804, and 806 (step 1104). After the initialcompression and optional stretching, the mattress or foam pad mayundergo a further stretching in a direction perpendicular to the initialoptional stretching in the exemplary apparatus of FIG. 10, by rollerpairs 1002 and 1004 (step 1106). Finally, the process may end at step1108, and may repeat. In certain embodiments, step 1106 may occur beforestep 1104, or even occur simultaneously. In all of the aboveembodiments, the stressing, compression, and/or stretching of themattress or foam pad may be temporary, in that the stressing,compressing, and/or stretching force is only applied for a finite periodof time, and after the force is no longer applied, the mattress and/orfoam pad dimensions remain substantially similar to thepre-stressed/compressed/stretched dimensions.

Those skilled in the art will know or be able to ascertain using no morethan routine experimentation, many equivalents to the embodiments andpractices described herein. For example, the illustrative embodimentsdiscuss mattresses, but other cushions and furniture may be made withthe systems and methods described herein. As another example, it shouldbe understood that compressing, stressing or stretching a foam pad inone or more axial directions such that cell windows are broken may becovered by different embodiments of the present invention. Accordingly,it will be understood that the invention is not to be limited to theembodiments disclosed herein, but is to be understood from the followingclaims, which are to be interpreted as broadly as allowed under the law.

Variations, modifications, and other implementations of what isdescribed may be employed without departing from the spirit and scope ofthe invention. More specifically, any of the method, system and devicefeatures described above or incorporated by reference may be combinedwith any other suitable method, system or device features disclosedherein or incorporated by reference, and is within the scope of thecontemplated inventions. The systems and methods may be embodied inother specific forms without departing from the spirit or essentialcharacteristics thereof. The foregoing embodiments are therefore to beconsidered in all respects illustrative, rather than limiting of theinvention. The teachings of all references cited herein are herebyincorporated by reference in their entirety.

1. A system for pre-conditioning cushioning articles, comprising atleast a first pair of rollers including a first roller and a secondroller; a first support frame and a second support frame; and a hingesystem including at least one support spring, wherein the first rolleris separated from the second roller by a first gap; the first roller isrotationally coupled to the first support frame and the second roller isrotationally coupled to the second support frame; the hinge system isadjustably coupled to the first support frame and the second supportframe; the at least one support spring is attached to the first supportframe and configured to exert a first force on the second support framesufficient to maintain the first gap; and the first gap changes inresponse to adjustments in the hinge system.
 2. The system of claim 1,further comprising at least one freely rotating coupling, wherein atleast one of the first roller and the second roller is rotationallycoupled to the first or second support frame via the at least one freelyrotating coupling.
 3. The system of claim 1, further comprising at leastone roller driver coupling, wherein at least one of the first roller andthe second roller is rotationally coupled to the first or second supportframe via the at least one roller driver coupling.
 4. The system ofclaim 3, further comprising at least one motor assembly, wherein atleast one of the first roller and the second roller is rotationallycoupled to and actuatable by the motor assembly.
 5. The system of claim1, further comprising a second pair of rollers, wherein the first pairof rollers and the second pair of rollers are arranged in a seriesconfiguration and with degrees of freedom in both the vertical andmachine direction regarding set points, the first roller is a first toproller and the second roller is a first bottom roller, the first supportframe is a top support frame and the second support frame is a bottomsupport frame, the second pair of rollers includes a second top roller,rotationally coupled to the top support frame, and a second bottomroller, rotationally coupled to the bottom support frame, and separatedfrom each other by a second gap different from the first gap, the firstforce is sufficient to maintain the second gap; and the second gapchanges in response to adjustments in the hinge system.
 6. The system ofclaim 5, further comprising a third pair of rollers, wherein the thirdpair of rollers includes a third top roller, rotationally coupled to thetop support frame, and a third bottom roller, rotationally coupled tothe bottom support frame, and separated from each other by a third gapdifferent from the first gap and the second gap, the first force issufficient to maintain the third gap; and the third gap changes inresponse to adjustments in the hinge system.
 7. The system of claim 6,wherein the first pair of rollers, second pair of rollers and third pairof rollers are arranged in a series configuration and with degrees offreedom in both the vertical and machine direction regarding set points.8. The system of claim 6, wherein the first gap is about 2 inches, thesecond gap is about 1 inch, and the third gap is about 0.5 inches.